/*
 * Created on 02-Jan-2005
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package org.gudy.azureus2.core3.tracker.server.impl.tcp.nonblocking;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.List;

import org.gudy.azureus2.core3.config.COConfigurationManager;
import org.gudy.azureus2.core3.config.ParameterListener;
import org.gudy.azureus2.core3.logging.LogAlert;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.tracker.server.TRTrackerServerException;
import org.gudy.azureus2.core3.tracker.server.impl.tcp.TRTrackerServerTCP;
import org.gudy.azureus2.core3.util.AEMonitor;
import org.gudy.azureus2.core3.util.AEThread;
import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.SystemTime;

import com.aelitis.azureus.core.networkmanager.VirtualChannelSelector;
import com.aelitis.azureus.core.networkmanager.VirtualServerChannelSelector;
import com.aelitis.azureus.core.networkmanager.VirtualServerChannelSelectorFactory;
import com.aelitis.azureus.core.networkmanager.admin.NetworkAdmin;

/**
 * @author parg
 * 
 */

public class TRNonBlockingServer extends TRTrackerServerTCP implements VirtualServerChannelSelector.SelectListener {
    private static final LogIDs LOGID = LogIDs.TRACKER;
    private static final int TIMEOUT_CHECK_INTERVAL = 10 * 1000; // 10sec

    private static final int CLOSE_DELAY = 5 * 1000;

    private static int SELECT_LOOP_TIME;

    static {
        COConfigurationManager.addAndFireParameterListeners(new String[] { "network.tracker.tcp.select.time", }, new ParameterListener() {
            public void parameterChanged(String name) {
                SELECT_LOOP_TIME = COConfigurationManager.getIntParameter("network.tracker.tcp.select.time", 100);
            }
        });
    }

    private TRNonBlockingServerProcessorFactory processor_factory;

    private final VirtualChannelSelector read_selector;
    private final VirtualChannelSelector write_selector;

    private List connections_to_close = new ArrayList();

    private List processors = new ArrayList();

    /*
     * private long last_stats_time; private long last_timeouts; private long last_connections;
     */

    private InetAddress current_bind_ip;

    private long total_timeouts;
    private long total_connections;

    public static final int MAX_CONCURRENT_CONNECTIONS = COConfigurationManager.getIntParameter("Tracker TCP NonBlocking Conc Max");

    private final AEMonitor this_mon = new AEMonitor("TRNonBlockingServer");

    private VirtualServerChannelSelector accept_server;

    private boolean immediate_close = COConfigurationManager.getBooleanParameter("Tracker TCP NonBlocking Immediate Close");

    private volatile boolean closed;

    public TRNonBlockingServer(String _name, int _port, InetAddress _bind_ip, boolean _apply_ip_filter,
            TRNonBlockingServerProcessorFactory _processor_factory)

    throws TRTrackerServerException {
        this(_name, _port, _bind_ip, _apply_ip_filter, true, _processor_factory);
    }

    public TRNonBlockingServer(String _name, int _port, InetAddress _bind_ip, boolean _apply_ip_filter, boolean _start_up_ready,
            TRNonBlockingServerProcessorFactory _processor_factory)

    throws TRTrackerServerException {
        super(_name, _port, false, _apply_ip_filter, _start_up_ready);

        processor_factory = _processor_factory;

        read_selector = new VirtualChannelSelector(_name + ":" + _port, VirtualChannelSelector.OP_READ, false);
        write_selector = new VirtualChannelSelector(_name + ":" + _port, VirtualChannelSelector.OP_WRITE, true);

        boolean ok = false;

        if (_port == 0) {

            throw (new TRTrackerServerException("port of 0 not currently supported"));
        }

        try {
            InetSocketAddress address;

            if (_bind_ip == null) {

                _bind_ip = NetworkAdmin.getSingleton().getSingleHomedServiceBindAddress();

                if (_bind_ip == null) {

                    address = new InetSocketAddress(_port);

                } else {

                    current_bind_ip = _bind_ip;

                    address = new InetSocketAddress(_bind_ip, _port);
                }
            } else {

                current_bind_ip = _bind_ip;

                address = new InetSocketAddress(_bind_ip, _port);
            }

            accept_server = VirtualServerChannelSelectorFactory.createBlocking(address, 0, this);

            accept_server.start();

            AEThread read_thread = new AEThread("TRTrackerServer:readSelector") {
                public void runSupport() {
                    selectLoop(read_selector);
                }
            };

            read_thread.setDaemon(true);

            read_thread.start();

            AEThread write_thread = new AEThread("TRTrackerServer:writeSelector") {
                public void runSupport() {
                    selectLoop(write_selector);
                }
            };

            write_thread.setDaemon(true);

            write_thread.start();

            AEThread close_thread = new AEThread("TRTrackerServer:closeScheduler") {
                public void runSupport() {
                    closeLoop();
                }
            };

            close_thread.setDaemon(true);

            close_thread.start();

            Logger.log(new LogEvent(LOGID, "TRTrackerServer: Non-blocking listener established on port " + getPort()));

            ok = true;

        } catch (Throwable e) {

            Logger.logTextResource(new LogAlert(LogAlert.UNREPEATABLE, LogAlert.AT_ERROR, "Tracker.alert.listenfail"), new String[] { ""
                    + getPort() });

            throw (new TRTrackerServerException("TRTrackerServer: accept fails", e));

        } finally {

            if (!ok) {

                destroySupport();
            }
        }
    }

    public InetAddress getBindIP() {
        return (current_bind_ip);
    }

    public void setImmediateClose(boolean immediate) {
        immediate_close = immediate;
    }

    protected void selectLoop(VirtualChannelSelector selector) {
        long last_time = 0;

        while (!closed) {

            try {
                selector.select(SELECT_LOOP_TIME);

                // only use one selector to trigger the timeouts!

                if (selector == read_selector) {

                    long now = SystemTime.getCurrentTime();

                    if (now < last_time) {

                        last_time = now;

                    } else if (now - last_time >= TIMEOUT_CHECK_INTERVAL) {

                        last_time = now;

                        checkTimeouts(now);
                    }
                }
            } catch (Throwable e) {

                Debug.printStackTrace(e);
            }
        }
    }

    public void newConnectionAccepted(ServerSocketChannel server, SocketChannel channel) {
        final TRNonBlockingServerProcessor processor = processor_factory.create(this, channel);

        int num_processors;

        try {
            this_mon.enter();

            total_connections++;

            processors.add(processor);

            num_processors = processors.size();

        } finally {

            this_mon.exit();
        }

        if (MAX_CONCURRENT_CONNECTIONS != 0 && num_processors > MAX_CONCURRENT_CONNECTIONS) {

            removeAndCloseConnection(processor);

        } else if (isIPFilterEnabled() && ip_filter.isInRange(channel.socket().getInetAddress().getHostAddress(), "Tracker", null)) {

            removeAndCloseConnection(processor);

        } else {

            VirtualChannelSelector.VirtualSelectorListener read_listener = new VirtualChannelSelector.VirtualSelectorListener() {
                private boolean selector_registered;

                public boolean selectSuccess(VirtualChannelSelector selector, SocketChannel sc, Object attachment) {
                    try {
                        int read_result = processor.processRead();

                        if (read_result == 0) { // read processing is complete

                            if (selector_registered) {

                                read_selector.pauseSelects(sc);
                            }

                        } else if (read_result < 0) { // a read error occured

                            removeAndCloseConnection(processor);

                        } else {
                            // more reading required

                            if (!selector_registered) {

                                selector_registered = true;

                                read_selector.register(sc, this, null);

                            } else {

                                read_selector.resumeSelects(sc);
                            }
                        }

                        return (read_result != 2);

                    } catch (Throwable e) {

                        Debug.printStackTrace(e);

                        removeAndCloseConnection(processor);

                        return (false);
                    }
                }

                public void selectFailure(VirtualChannelSelector selector, SocketChannel sc, Object attachment, Throwable msg) {
                    removeAndCloseConnection(processor);
                }
            };

            processor.setReadListener(read_listener);

            read_listener.selectSuccess(read_selector, channel, null);
        }
    }

    protected void readyToWrite(final TRNonBlockingServerProcessor processor) {
        VirtualChannelSelector.VirtualSelectorListener write_listener = processor.getWriteListener();

        if (write_listener == null) {

            write_listener = new VirtualChannelSelector.VirtualSelectorListener() {
                private boolean selector_registered;

                public boolean selectSuccess(VirtualChannelSelector selector, SocketChannel sc, Object attachment) {
                    try {
                        int write_result = processor.processWrite();

                        if (write_result > 0) { // more writing is needed

                            if (selector_registered) {

                                write_selector.resumeSelects(sc); // resume for more writing

                            } else {

                                selector_registered = true;

                                write_selector.register(sc, this, null);
                            }

                        } else if (write_result == 0) { // write processing is complete

                            if (processor.getKeepAlive()) {

                                processor.getReadListener().selectSuccess(read_selector, sc, null);

                            } else {

                                removeAndCloseConnection(processor);
                            }

                        } else if (write_result < 0) { // a write error occured

                            processor.failed();

                            removeAndCloseConnection(processor);
                        }

                        return (write_result != 2);

                    } catch (Throwable e) {

                        Debug.printStackTrace(e);

                        removeAndCloseConnection(processor);

                        return (false);
                    }
                }

                public void selectFailure(VirtualChannelSelector selector, SocketChannel sc, Object attachment, Throwable msg) {
                    removeAndCloseConnection(processor);
                }
            };

            processor.setWriteListener(write_listener);
        }

        write_listener.selectSuccess(write_selector, processor.getSocketChannel(), null);
    }

    protected void removeAndCloseConnection(TRNonBlockingServerProcessor processor) {
        processor.completed();

        try {
            this_mon.enter();

            if (processors.remove(processor)) {

                read_selector.cancel(processor.getSocketChannel());
                write_selector.cancel(processor.getSocketChannel());

                if (immediate_close) {

                    try {
                        processor.closed();

                        processor.getSocketChannel().close();

                    } catch (Throwable e) {

                    }
                } else {

                    connections_to_close.add(processor);
                }
            }

        } finally {

            this_mon.exit();
        }
    }

    public void checkTimeouts(long now) {
        // we don't particularly care about timeouts if nothing's going on, hence we only
        // trigger the check on the arrival of a new connection

        /*
         * String con_rate = ""; String tim_rate = ""; if ( last_stats_time > 0 ){ long time_diff = (now - last_stats_time)/1000; long conn_diff =
         * total_connections - last_connections; long tim_diff = total_timeouts - last_timeouts; con_rate = "" + (conn_diff/time_diff); tim_rate = ""
         * + (tim_diff/time_diff); } System.out.println( "Tracker: con/sec = " + con_rate + ", timeout/sec = " + tim_rate + ", tot_con = " +
         * total_connections+ ", total timeouts = " + total_timeouts + ", current connections = " + processors.size() + ", closing = " +
         * connections_to_close.size()); last_stats_time = now; last_connections = total_connections; last_timeouts = total_timeouts;
         */

        try {
            this_mon.enter();

            List new_processors = new ArrayList(processors.size());

            for (int i = 0; i < processors.size(); i++) {

                TRNonBlockingServerProcessor processor = (TRNonBlockingServerProcessor) processors.get(i);

                if (now - processor.getStartTime() > PROCESSING_GET_LIMIT && !processor.areTimeoutsDisabled()) {

                    read_selector.cancel(processor.getSocketChannel());
                    write_selector.cancel(processor.getSocketChannel());

                    connections_to_close.add(processor);

                    total_timeouts++;

                } else {

                    new_processors.add(processor);
                }
            }

            processors = new_processors;

        } finally {

            this_mon.exit();
        }
    }

    public void closeLoop() {
        // socket channel close ops can block, hence we move it off the main processing loops
        // to ensure that a rogue connection doesn't stall us

        List pending_list = new ArrayList();

        long default_delay = CLOSE_DELAY * 2 / 3;

        long delay = default_delay;

        while (!closed) {

            // wait a small amount of time to allow the client to close the connection rather
            // than us. This prevents a buildup of TIME_WAIT state sockets

            if (delay > 0) {

                try {
                    Thread.sleep(delay);

                } catch (Throwable e) {

                    Debug.printStackTrace(e);
                }
            }

            // System.out.println( "close delay = " + delay + ", pending =" + pending_list.size());

            long start = SystemTime.getCurrentTime();

            for (int i = 0; i < pending_list.size(); i++) {

                try {
                    TRNonBlockingServerProcessor processor = (TRNonBlockingServerProcessor) pending_list.get(i);

                    processor.closed();

                    processor.getSocketChannel().close();

                } catch (Throwable e) {

                }
            }

            try {
                this_mon.enter();

                pending_list = connections_to_close;

                connections_to_close = new ArrayList();

            } finally {

                this_mon.exit();
            }

            // reduce the sleep time if we're not keeping up

            long duration = SystemTime.getCurrentTime() - start;

            if (duration < 0) {

                duration = 0;
            }

            delay = default_delay - duration;
        }
    }

    protected void closeSupport() {
        closed = true;

        accept_server.stop();

        destroySupport();
    }
}
